Re:Serial Port SDR
by IIAOPSW on Thursday December 06, 2018 @09:12AM
(#18618148)
Well now we know what radio waves are produced by 0x55. How about other characters? I'm willing to bet that everyone's wired keyboard is an SDR so to speak and a well placed receiver can keylog you.
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Sure. A classic article from 1990: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.35.9...
An interesting thing from reading about practical experiments in EM eavesdropping is that it's not just the obvious emanations that you have to worry about. Your sidechannels have sidechannels. In that paper, for example, the actual communication radiates and can be received in the shortwave band, but also a frequency-modulated version of it appears in the FM radio band. Presumably a bit of power-supply droop is modulating a local oscillator causing it to transmit a clear signal.
Most keyboards don't have an antenna attached. While you can keylog a keyboard via emissions like this, you have to have physical access to the office to do so - at that point putting a usb keylogger inline with the keyboard is easier and more reliable. (or substitution your own keyboard with a real radio)
>Most keyboards don't have an antenna attached.
What about meter long wire that runs from the keyboard to the back of the tower.
it is twisted pair. Not great shielding, but enough to make the signal weak.
Why office? Imagine such keyloggers under tables in public spaces where people can put their laptops.
I wonder how fast you could toggle the capslock LED... hmm
Via Xlib, with USB keyboard, 10 Hz starts to become uncomfortable, 10% in system time.
Had to test ! :)